Heating element

ABSTRACT

The invention relates to a heating element comprising a base body ( 4 ) made of metal, preferably aluminum or stainless steel, the surface ( 10 ) of which is highly polished and corrosion resistant.

FIELD OF THE INVENTION

The invention relates to heating bodies, and in particular, to toweldryers for drying and warming towels.

BACKGROUND OF THE INVENTION

Towel dryers are used to dry and warm towels. A towel dryer has an outersurface that supports a towel to be dried. The surface is heated aboveroom temperature, typically by flowing heated fluid through the dryer orby electrical heating.

It is believed that a towel dryer operates mainly by transferring heatto the towel by conduction and natural convection. Heat is transferredby conduction directly from the dryer surface to the portion of thetowel in contact with the surface. Heat is also transferred indirectlyfrom the towel dryer to the towel by natural convection, the towel dryerheating the surrounding air and the heated air transferring heat to thetowel.

It is believed that at normal operating temperatures, radiant heattransfer is not an important mechanism in transferring heat from thetowel dryer to the towel. However, heat can be lost from the towel dryerby such radiant heat transfer. Heat loss by radiant heat transfer wastesenergy and lowers the efficiency of the towel dryer because radiant heattransfer cools the dryer surface without effectively contributing towarming and drying the towel. Reducing heat loss by radiant heattransfer would enable the towel dryer to be more energy efficient: thetowel dryer could reach a higher operating temperature with the sameenergy input, or would reach the same operating temperature with reducedenergy input.

Towel dryers are generally constructed of a base body of unalloyed steelwith a surface coating, in order to attain certain desirable colorationappearances. In this practice, depending upon the location of the saidtowel dryer, different coating procedures are used. Thus it is possible,for example, that towel dryers in residential areas are provided with apowdery coating or they may be lacquered. Most likely a towel dryer in abathroom can be electrically chromed.

The above described procedures and materials have the disadvantage, thatthe surface coating negatively affects the heating capacity of a steeltowel dryer. The term “heating capacity” is related to the amount ofenergy that must be supplied to maintain the towel dryer at itsoperating temperature. A towel dryer with a higher heating capacity willmaintain its operating temperature with less energy input than would asimilar towel dryer with a lower heating capacity.

Thus, for example, an electrically chromed, steel towel dryer, ascompared to a lacquered or powder covered steel towel dryer, will yieldonly 20 to 30% as much heat. This poor rendition of heat from chromecovered steel heating bodies results in the construction of very largeheating bodies, which in turn, each disadvantageously require a largespace allotment.

It is believed that a chromed steel body loses more heat by radiant heattransfer than a lacquered or powder covered steel body. This appears tobe due to the higher emissivity of the chromed steel body as compared tothe lacquered or powder covered steel body. The greater the emissivity abody has, the more efficient it is in losing heat by radiant heattransfer. The higher emissivity of the chromed steel body causes greaterheat loss through radiant heat transfer, reducing the heating capacityof the body and reducing the energy efficiency of the towel dryer.

The purpose of the present invention is to create a towel dryer with asimilar, highly reflective surface, which resembles a towel dryer havinga chromed body, which sets aside the above named disadvantages and isfurther, simple and economical to produce. In other words, the purposeof the present invention is to provide a functionally more energyefficient towel dryer that retains a visually appealing, highlyreflective body. The towel dryer would be capable of transferring alarger percentage of its heat by conduction or convection, and so couldalso be made smaller for the same rate of heat transfer to a towel.

SUMMARY OF THE INVENTION

The towel dryer in accord with the invention has a base body of metal,especially aluminum. The surface of the said invented base body isworked in such a manner, that a conventional electrically applied chromecoating or gilding, for the purpose of and bringing about a highlyreflective surface, can be eliminated. Instead of aluminum, it is alsopossible to make use of any other metal, such as, for instance, a highlyrefined steel.

Highly polished aluminum may have an emissivity of about 0.04 or less,and highly polished stainless steel may have an emissivity of about 0.1,each significantly lower than the emissivity of chromed steel that maybe about 0.17. A towel dryer made of highly polished aluminum or highlypolished stainless steel would have less radiant energy loss and thusgreater heating capacity and greater operating efficiency than would thesame conventional towel dryer made of chromed steel.

In accord with the invention, the surface is then of high polish andpossesses a degree of reflectivity of 80% to 100%. This provides a bodyhaving a sufficiently low emissivity to be more efficient than aconventional chromed steel towel dryer.

Because of the aluminum, that is to say a metallic, base body and theelimination of the electrical chrome application, the invented toweldryer has a substantially greater thermal efficiency than does a toweldryer having the conventional chromed, steel heating body. Thus, aconventional towel dryer, which possesses a chromed coating, whencompared to an invented, highly polished towel dryer constructed ofaluminum, exhibits a thermal efficiency which is about 30% to 40% less.In other words, the invented towel dryer, when operating at the sameheating load, can clearly be made smaller and less expensively. This isa considerable advantage in bathrooms with predominately less availablespace.

For the achievement of the desired degree of burnish, the metalconstruction of the invented towel dryer base body is mechanicallyground, mechanically polished and chemically and electrochemicallypolished.

One embodiment of the invented towel dryer advantageously possesses, forthe purpose of increasing the resistance to corrosion and for theretention of the high degree of burnish, an electrochemically anodizedsurface or has an Eloxal coating. Plain anodized aluminum may have anemissivity of 0.04, which enables a towel dryer having polished aluminumsurface to be anodized for corrosion resistance and yet retain a loweremissivity than a conventional chromed steel towel dryer.

Another embodiment provides, for the increase of resistance tocorrosion, and for the retention of the high degree of burnish, a clearlacquer coating.

Intrinsically, known towel dryers with an aluminum base body are oftenchromed for the purpose of creating a highly reflective surface, whichrequires not only a complicated procedure and is expensive, but further,notably reduces the emission of heat, that is, notably reduces theheating capacity and energy efficiency of the towel dryer.

In the following, the invention is more closely described with the aidof an illustrated presentation of a preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a perspective view of an invented towel dryer.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The invented towel dryer 2 has a base body 4 and two connection fittings6, 8 connecting respectively to an inlet line for water supply and to anoutlet line for the removal of the used water. The external inlet andoutlet lines are not shown. The base body 4 has two parallel runningtubes 12, 14, which are distanced from one another by the crossovertubes 16. With this arrangement, the water can flow between the twotubes 12, 14, so that, for example, hand towels (not shown) can be hungon the crossover tubes 16 to be dried.

In accord with the invention, the base body requires no surface coatingfor the attainment of the desired degree of reflectivity, but rather thesurface is worked in such a manner, that both the aesthetic totalimpression of the heating body 2 is increased and the base body is alsoprotected against corrosion and damage.

In a preferred embodiment, the surface possesses a degree ofreflectivity of 80% to 100%.

As an aid for the judgment of the luster of the finish, a reflectometeris applicable, which is in accord with DIN 67 530.

An essential advantage of the invented towel dryer 2 is, that incomparison to conventional chromed steel towel dryers, it possesses animproved degree of heat transfer. For example, of a chromed heatingbody, the statement is made, that a heat load of some 750 W isdeveloped. Contrary to this, an equally sized aluminum towel dryer 2develops a heating load of about 1100 W. That is to say, the inventedtowel dryer 2 possesses, size for size, about a 50% greater heatproduction, whereby its high heat transfer capability permits a quickerreaction for the input and output control, such as, for example, mightbe called for by thermostatic regulation. Such an advantage can markedlyreduce the heating costs.

The metal base body 4 of the towel dryer 2, in keeping with theinvention, is mechanically ground for the achievement of the desireddegree of reflectivity, then mechanically polished and chemically(electro-chemically) brought to a high reflectivity.

The mechanical abrasive treatment is mostly done by rough grinding forthe removal of gross protrusions and depressions of the surface 10. Thisis generally carried out by a grinding disk. In general dry grinding isemployed, whereby the circumferential speed is held to within a range of420 to 1200 RPM.

After the rough grinding, then a secondary grinding takes place. Forthis operation, advantageously, a grinding disk arrangement is againused wherein the laminated disks are impregnated with special clay. The60 to 120 mesh clay is impregnated into a fabric which can be of cloth,sheepskin, or muslin. The disks may turn within a range of 1500 to 1800RPM. However, even a rotation speed up to 3000 RPM may be used.

Subsequent to the secondary grinding, fine abrasive treatment takesplace. This can also be known as pre-polishing. Normally, the disks forthis purpose, as described above, can be of felt, sheepskin or bias cutmuslin fabric with impregnated 100 to 200 mesh clay. The operation iscooled by air flow. The circumferential speed lies somewhere in theranges as given above, although it may be slightly increased.

After the mechanical grinding, the surface 10, for the removal ofabrasion traces, and for the acquiring of a luster, is similarlymechanically treated, this time with a polishing disk. The polishingdisk possesses more laminations, preferably of loose or battened cottonmaterial and turns at some 2000 to 2600 RPM. This polishing isoptionally carried out dry or wet. In order that the hardness of thepolishing disk may be changed, it is possible, that among other changesof a fiber count of the cotton material, also cloth, wood or paperinsertions may be interposed between the individual disks.

Care must be taken, in regard to the mechanical polishing of theinvented towel dryer, that, in particular, no metal particulate are tobe allowed to adhere to the polishing disks, since such inserts, withoutfail, lead to a lessening of the surface quality.

Fundamentally, attention must be given during the mechanical grindingand polishing, that no excessive temperatures are generated and nogouging of the surface takes place. A protection of such temperature canbe brought about, for the safety of the surface, by an appropriatechoice of the speed of rotation, pressure of the abrasive means, as wellas by means of proper design of the said disks or by the use of abrasiveor polishing means such as greases, oil or pastes.

By the employment of abrasive and/or polishing means, the impingement ofthese materials in the surface 10 is to be avoided, since such embeddedmaterials can be released during the next process step and thus impairthe quality of the surface 10.

Further, in a case of large towel dryers 2 with greater surfaces 10, itcan be of advantage, to replace the grinding disks with abrasive belts.

For the achievement of a final luster, the surface 10 is treated, afterthe mechanical phase, chemically or electrochemically. Preference isgiven to the chemical treatment, since such a procedure, counter to theelectrochemical method, such as, for instance, the Erft-works processhas the advantage, that no electrical energy is required. In this way,instead of electrical current, oxidizing agents are used.

Advantageously, the surface 10 is finally electrochemically anodized, ortreated with Eloxal, so that the resistance to corrosion of the saidsurface is increased by an Eloxal-coating. This is especially valuable,if the heating body 2 is to be used in rooms subject to high humidity,such as, for example, bathrooms or, as mentioned above, the heating bodyis to be used for the drying of towels.

By the above, the surface 10 is chemically changed, so that a porousaluminum oxide layer is formed, which is still to be sealed in a finalstep of the process.

It is also possible, that the surface 10, instead of being coated withthe Eloxal layer, receives a finish of a clear lacquer for the increaseof the resistance to corrosion. In this case, the lacquer coating can beapplied by spraying, or in the form of a powder, or by means of a finebrush, or the lacquer can be applied by dipping into an immersion bath.

Disclosed is a towel dryer with a base body of metal, preferablyaluminum or high quality steel, the surface of which, is caused to be ofhigh reflectivity and resistant to corrosion.

REFERENCE NUMBERS AND CORRESPONDING COMPONENTS

-   -   2 Towel dryer    -   4 Base body    -   6 Connection fitting    -   8 Connection fitting    -   10 Surface    -   12 Parallel tube    -   14 Parallel tube    -   16 Crossover tube(s)

1. A towel dryer comprising an aluminum body, the body comprising asurface configured to contact and transfer heat to a towel to be dried,the surface having a degree of reflectance not less than 80%, and aclear lacquer coat on the aluminum surface.